1. The Field of the Invention
The present invention is directed to optical transmitters.
2. The Relevant Technology
In some laser transmitters, a laser is operated at a high bias level and modulated to produce adiabatically chirped pulses that are modulated both as to frequency and amplitude. An optical spectrum reshaper (OSR) having a frequency dependent transmission profile receives the output of the laser and outputs a signal having an enhanced amplitude modulation. The OSR increases the extinction ratio by converting frequency modulation to amplitude modulation.
In such systems, rapid frequency modulation is required. Although many lasers may be tuned to different frequencies, not all may be frequency modulated at data rates in excess of 10 gigabits per second (Gb/s). Furthermore, lasers capable of adequate frequency modulation rates are either not capable of doing so across a broad range of carrier frequencies or do not produce pulses suitable for use in such systems.
In view of the foregoing it would be an advancement in the art to provide a directly modulated tunable laser suitable for use in combination with an OSR at data rates in excess of 10 Gb/s and over a broad range of frequencies.